Exercise inhibits fat formation, and serves as a stimulus to form bone and muscle. While increased calorie use during strenuous activity helps to suppress fat accumulation, we have found that adipogenesis in vitro, and adiposity in vivo can also be inhibited in a calorie independent manner by mechanically biasing mesenchymal stem cells (MSCs) to favor differentiation towards a musculoskeletal, rather than an adipose fate. The ability to define stem cell lineage by mechanical signals suggests that a 'developmental' rather than a 'metabolic' strategy could be employed to prevent and/or treat diseases such as obesity, diabetes and osteoporosis. In marked contrast to bone/fat outcomes generated by prolonged exercise, we have shown that Low Intensity Vibration (LIV) produces an anabolic response in bone and a marked suppression of fat after short daily treatment time (<20 minutes per day) with high frequency (30-90Hz), extremely low intensity (<1.0g) mechanical signals. Translating this mechanosensitivity to the clinic, LIV can be delivered to the standing human with high efficiency (~70%), and is considered safe by both ISO and NIOSH for exposures up to 4 hours each day. This BRP is designed to improve our understanding of the physical and biological basis of regulating MSC fate with mechanical signals, and thereby improve our ability to translate this to the clinic as an optimized non- drug based intervention to prevent or reverse obesity and diabetes, while simultaneously suppressing osteopenia. Through three integrated specific aims, this BRP will examine the: 1) Biologic Mechanism of LIV: using primary MSCs, we will define specific molecular pathways which control - and maximize - the biologic responsiveness of MSC populations to these mechanical signals (e.g., incorporating recovery periods between mechanical bouts allows for amplification of the biologic response), with efforts to define which components of cell architecture contribute to the response; 2) Optimization of LIV Signal: by integrating finite element modeling with in vitro studies, we will work towards establishing the mechanical environment to which MSC are exposed during LIV, and identify those specific parameters that contribute to the efficacy of the LIV signal, providing the basis for optimizing the LIV signal. 3) Translational Potential of LIV: a the level of the whole animal, examine the degree to which optimized LIV signal and scheduling suppresses the fat phenotype in mouse models of diet-induced obesity and estrogen deficiency (ovariectomy), achieved through the regulation of MSC activity, and the extent to which downstream complications of diabesity, including insulin sensitivity, tissue steatosis, elevated triglycerides, free fatty acids and adipokines, are mitigated through exposure to LIV over extended periods of time. In sum, this BRP lies at the convergence of engineering, molecular biology, biophysics and medicine to understand how mechanical signals regulate MSC cell fate, with the ultimate goal of harnessing this sensitivity towards a bioengineering based, non-pharmacologic intervention for the suppression of diabesity, particularly excess visceral adiposity, in those at high risk for obesity and diabetes. PUBLIC HEALTH RELEVANCE: This BRP is designed, through three interconnected specific aims, to better understand how low intensity vibration (LIV) effectively bias mesenchymal stem cell differentiation away from adipogenesis (fat formation) and towards osteoblastogenesis (bone formation), and to establish whether this science can translate to the clinic as a non-pharmacological intervention to suppress chronic diseases such as diabesity.